The present invention relates generally to support structures and more particularly to integrated steering column, instrument panel, and cowl body structure for use in vehicles.
It is known in the prior art to provide cross car support structure for an instrument panel assembly in a vehicle. The typical cross car support structure must support many instrument panel components, such as steering wheels, air bag modules, HVAC modules, and glove boxes. Traditionally, most instrument panel support structures include a metal beam made of stamped steel or magnesium.
It has also been suggested to provide cross car beam structures having composite compositions reinforced with metal. When mainly plastic or composite-type cross car beams have been used, they are typically composed of several pieces which have relatively complex shapes and which are stacked together and attached in a complicated manner to provide sufficient strength or require additional metal cross beams or mounting brackets.
In addition to instrument panel support structures, vehicles typically have a separate cowl support structure located between the instrument panel and the engine. This cowl support structure is typically a complex stamped steel weldment fabrication and is made to support structures such as wiper motor mounts, wiper pivot journals and fulcrums, hood hinge mounts, AC/heater mounts, or brake boosters. Similar to the instrument panel support structure, strategies have been incorporated to ensure that the cowl structure itself can support the various components and attempts have been made to utilize alternative materials such as plastics for weight savings.
However, the instrument panel support structure and the cowl support structure exist as separate, and at times, antagonistic components. These components create unnecessary redundant support structure, weight, and packaging space. Further, as two separate structures, body stiffness is less than desirable.
It is thus highly desirable to combine the instrument panel support structure and cowl support structure into one integrated support structure that eliminates these problems, and to do so in a manner which provides modular components for ease of assembly and versatility.
It is an object of the present invention to bring together the instrument panel support structure, steering column support structure and cowl structure to a shared, dependent, and highly complementary support structure between the A-Pillars. The above object is accomplished by clam-shelling the proposed cowl and instrument panel casting together to create an integrated, rigid, chamber-like structure.
The integrated casting provides many benefits over previous designs. First, the new casting provides substantial weight savings both through the use of magnesium to replace steel in the prior art and because the new design eliminates redundant support and component structure. The elimination of redundancy also creates extra packaging space within the vehicle. Also, the decreased weight in the upper portion improves rollover stability by lowering the center of gravity within the vehicle.
By maximizing cast-in features, the present invention also eliminates parts and secondary operations, resulting in potentially substantial cost savings and further decreasing the weight within the vehicle. Dimensional control and repeatability within the casting allows for increased margin control, which results in a casting with component boundaries with less squeak and rattle potential.
In addition, the magnesium clamshell structure is designed having similar or superior bending and torsional strength as compared to traditional steel structures. The clamshell shape is structural in that it uses a matched xe2x80x9cIxe2x80x9d value for the mechanical properties of magnesium.
Also, the hollow resultant clamshell structure offers advantages for packaging and air movement. First, wires or other secondary components may be placed within the hollow section in an area that is not easily accessible. Further, this hollow area within the clam shell castings is ideal for moving air for heating and cooling throughout the passenger compartment. It is contemplated that by integrating additional features within the castings, this air movement can be moved from the hollow structure, through the A pillars, into the doors, and into the B pillars of the vehicle. This airflow can move through the hollow structure itself, or through a sleeve placed within the hollow structure.
In addition, it is contemplated the front section of the casting may be cast into a three-piece modular unit, wherein the resultant castings may be assembled for use on vehicles for use on right-side or left-side drive vehicles.